Internal fixation #1 Flashcards Preview

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Flashcards in Internal fixation #1 Deck (34):
1

Big advantage of internal fixation is?

attached directly to bone and so provides more rigid stabilization than external coaptation

2

Fractures for which internal fixation is better than than external coaptation (5)

open fracture
fractures of the femur humerus and pelvis
articular fractures
obliqueor comminuted fractures
fractures with tension

3

intramedullary pins control what force well?

bending

4

Are IM pins often used alone?

No

5

4 advantages of IM pins

Availability
Axial alignment
Bending control
minimal blood supply disruption

6

What is cyclic fatigue?

Think of how you break a paper clip

7

4 disadvantages of IM pins

only control bending
anatomic repair required
Potential injury to surrounding structures
Not good in any flat or curvy bones

8

Which bone should never ever ever ever be pinned?

Radius

9

How does an IM pin cause potential injury to surrounding tissues?

Usually atleast one end is sticking out to some extent into the soft tissue

10

2 ways to place an IM pin?

Normograde
Retrograde

11

Describe normograde placement of an IM pin?

Line up fracture fragments and then run the pin down from one end to the other
tibial fractures

12

Describe retrograde placement

Start by placing the pin the proximal fragment via the fracture site, put it all the way until just the tip is in the fracture site then reduce and alignt he fracture and push it down intot he distal fragment

13

Advantage to retrograde placement?

Cant miss medullary cavity

14

Disadvantages to retrograde placement?

Surgical approach at fracture site needed
In the tibia the proximal side of the pin will come out into a joint so it is not an option

15

Disadvantages to retrograde placement?

Surgical approach at fracture site needed
In the tibia the proximal side of the pin will come out into a joint so it is not an option

16

How big should the diameter of the pin be? What about when combined with a bone plate?

60%of the medullary canal
50% of medullary canal

17

Should the IM pin penetrate the diatal fragment cortex?

NO there is invariable a joint there

18

Cross pinning crosses what?

two cortices as well as the fracture line

19

When is cross pinning approriate

Repairing physeal or very distal/proximal fractures

20

What forces does cross pinning neutralize?

bending, torsion and compression

21

When can wiring techniques be useful? (4)

Prevent propogation of fissures
reconstruct fragments to aid in reduction
hold things in place temporarily
Help an IM pin control torsional or compressive forces

22

When should full cerclage be used?

Long oblique fractures

23

What constitutes a long oblique fracture?

length of fracture is > than 2 times the diameter of the bone

24

Why do we always place cerclage wires in groups of 2

because one acts a fulcrum to concentrate forces on the fracture line

25

What is interfragmentary wiring

Placing wires between 2 fragments to connect them

26

What are 3 wiring techniques

Full cerclage
interfragmentary wiring
tension band wiring

27

Tension band wiring is done to counteract what forces/

Tension

28

Describe tension band wirring?

2 small pins perpendicular tot he fracture line
a figure 8 of wire is then passed through a hole distal to the fracture and the apparatus is looped over those 2 pins and tightend to turn the bad tension into good tension

29

What is an interlocking nail

Psecially designed rod that is fixed in place with bolts that pass through the rod itself and back through the cortex of the bone

30

forces controlled by interlocking nails

bending
compression
torsion
aaaand prevents the nail from migrating like in IM pinning

31

BIg advantage of interlocking nails?

Do not have to remove
Can fix comminuted fractures without anatomic reconstruction of the bone

32

What is the limitation of an interlocking nail?

need a bone protrusion proximally or distally to avoid going therough a joint

33

What is the limitation of an interlocking nail?

need a bone protrusion proximally or distally to avoid going therough a joint

34

Advantage of pin plate combination?

Drop diameter of the pin also only the most distal and most proximal screws for the plate have to do both cortices the rest can do 1